Alkaline nickel plating solutions

ABSTRACT

An alkaline nickel electroplating bath and process wherein brighter and more ductile nickel electroplate is formed due to the inclusion of addition agents which include certain organic amines, nitriles, unsaturated organic acids and heterocyclic compounds. Such plating processes are operable from room temperature to about 180*F over a current density range of 5 to 100 amps per sq. ft. Typical addition agents include 1,6Morpholino-2-hexyne; N-Allyl benzene sulfonamide; Sodium phosphite; Carboxymethylpyridinium iodide and 2-Phenyl-2Cyanoethoxybutyne.

United States Patent 9] Du Rose et al.

[ 51 Feb. 27, 1973 ALKALINE NICKEL PLATING SOLUTIONS [73] Assignee:Kewanee Oil Company, Bryn Mawr,

[22] Filed: June 14, 1971 [21] Appl. No.: 153,068

Related U.S. Application Data [63] Continuation of Ser. No. 752,169,Aug. 13, 1968,

2,978,391 4/1961 DuRose 3,114,687 12/1963 Brandt 3,133,006 5/1964 Ostrowet al. ..204/49 3,417,005 12/1968 Baig ..204/49 XR 3 ,428,5 36 2/1969Towle et al.. ..204/49 3,485,725 12/ 1969 Koretzky ..204/49 XR OTHERPUBLICATIONS Morton Schwartz, Tech. Proc. of the American ElectroplatersSoc., pp 176-183, (1960).

Primary Examiner-G. L. Kaplan Attorney-John P. Hazzard [5 7 ABSTRACT Analkaline nickel electroplating bath and process wherein brighter andmore ductile nickel electroplate is formed due to the inclusion ofaddition agents which include certain organic amines, nitriles,unsaturated organic acids and heterocyclic compounds. Such platingprocesses are operable from room temperature to about 180F over acurrent density range of 5 to 100 amps per sq. ft. Typical additionagents include 1,6-Morpholino-2-hexyne; N-Allyl benzene sulfonamide;Sodium phosphite; Carboxymethylpyridinium iodide and2-Phenyl-2-Cyanoethoxybutyne.

1 Claim, No Drawings ALKALINE NICKEL PLATING SOLUTIONS This applicationis a continuation of U.S. application Ser. No. 752,169 filed Aug. 13,1968, now abandoned.

This invention relates to the electrodeposition of nickel andnickel-cobalt alloys from alkaline plating solutions containing avariety of addition agents which includes certain organic amines,nitriles, unsaturated organic acids and heterocyclic compounds. Morespecifically, this invention is concerned with improving the brightnessof nickel deposits produced from alkaline baths and increasing thelimiting current density of said baths.

Alkaline nickel plating solutions have inherent advantages. The throwingpower of such solutions is almost invariably better than that observedin acid nickel solutions of the Watts or all-chloride variety. Forexample, the throwing power for alkaline nickel solutions using the BSIformula ranges from to 70 percent while that for the Watts solution is-5 to +5 percent. Moreover, when proper pro-plating steps are followed,a number of alkaline nickel formulations can be sued to plate nickeldirectly on zinc base die castings. This provides a distinct economicadvantage as it avoids the need for the use of cyanide copper which notonly eliminates the costly problem of waste disposal but affords abetter corrosion resistance.

Many complex alkaline nickel plating solutions of various formulationshave been proposed and devised heretofore. Their use, however, has notbeen extensive for several reasons, primarily because of a limitedcurrent density, lack of ductility, high stress and lack of lustre inthe deposit.

A variety of complexing agents has been used, see Saubestres review inPlating, May 1958. Complexing agents which have been used singly or incombination with others are: Nl-LOH (Brit. 512,484), triethanolamine asdescribed in J. Met. Fin. Soc. Japan 11 (2) (1960), citrate (Brit.880,786), hydroxyethylethylenediaminetriacetic acid (Brit. 1,022,073),and polyamines (U.S. 2,335,070). Also ammonia, citrate and pyrophosphateare used in combination as described in U.S. 2,069,566 and Brit.902,499. Similarly citrate, alkanolamines and EDTA type compounds aredescribed in U.S. 2,733,818.

Other complexing agents such as glycolic acid, tartarate, acetylacetone,and ethylenediamine may be used. Even glycerol and oxalate can be usedalthough they are used in combination with other agents having morecomplexing ability and solubility.

Little work has been done on producing bright or semibright nickeldeposits from alkaline solutions. Brit.

902,499 proposes the use of saccharin in combination with selenium,tellurium, arsenic or coumarin, while Brit. 880,786 uses saccharin and arather high concentration of formaldehyde.

At first thought one might assume that any addition agent or brightenerthat is useful in acid nickel plating solutions would be also useful andeffective in alkaline nickel solutions. This assumption has been shownmany times not to be true. In fact many brighteners and addition agentswhich are effective in acid baths of zinc, tin, antimony, copper andlead are ineffective and useless in the corresponding alkaline baths.Nickel is no exception. Table I is a list of compounds which exhibitlittle or no effect in alkaline nickel solutions.

Table I l. Phenylpropiolic acid (propiolic good) 2. 3-Methoxy-3-phenylbutyne-l 3. N-Propargyldibenzenesulfonamide 4. 2-(2-Propynyl)thiobenzothiazole 5. Allylsulfonate 6. Diallyl allylphosphonate 7. Allylarsonic acid 8. fl-Neopentylallyl alcohol 9.4-Methyl-4-pentene-2-ol l0. Undecyl-IO ene-l-ol l l. Methylbuteneol l2.Triallylamine l 3. Tetraallylethylenediamine 14. N Allyl saccharin 15.Cinnamyl alcohol 16.Crotonic acid 17. Butanediol l8. Glycerine l9.Cyclohexanol 20. Fuchsin 21. Phenol 22. Nitroindazole 23.Tetramethylene-bis-pyridinium chloride 24. Benzene sulfinic acid 25.Thiourea 26. Polyglycols and Pluronics It should be noted that compounds1 7, l2 14, 20 26 of above table are useful in acid nickel baths.

An important difference between the alkaline and acid nickel solutionsis that there appears to be very little, or consistent synergisticeffect due to the combination of so-called acid nickel control agentsand brighteners when they are sued in combination in the alkaline nickelsolution. In acid nickel solutions the use of the brightener along (suchas fuchsin, ethoxylated propargyl alcohol, ethylenecyanohydrin, etc.)usually gives only a slight increase in or uneven deposit brightness andthe deposit tends to be brittle. When a control agent such asnaphthalene sulfonate or saccharin is added the brightness anduniformity of brightness are enhanced and the ductility is improved.Very seldom is the above combination of any benefit in the alkalinenickel solution. For example ethoxylated butynediol at 0.2 g/l gives abright deposit up to about asf. At higher current densities the depositbecomes duller. By acid nickel standards the ductility is poor. When 1g/l of saccharin is added the deposit becomes duller especially in thelow current density area and slightly less ductile. A similar effect,i.e., no improvement, is noted when 3 g/l of N,N-bis-(phenylsulfonyl)-4,4'-bis-(phenylsulfonyl)- 4,4'-biphenyldisulfonimide is added to analkaline nickel solution containing butynediol.Tetramethylenebis-pyridinium chloride effects a streaked, semi-bright,very brittle deposit. The addition ofN,N'-bis-(phenylsulfonyl)-4,4'-biphenyldisulfonimide seemed to relievethe brittleness somewhat but darkened the deposit. N-Propargyl saccharineffects a bright deposit at 0.1 g/l with air agitation and the additionof N,N'-bis(phenylsulfonyl)- 4,4-biphenyldisulfonimide causes noimprovement in ductility or brightness. For some reason N-allylsaccharin which is similar to N-propargyl saccharin when used in theacid bath, has no effect when used in the alkaline solution.

In many cases as indicated above the addition of the sulfonate orsulfonamide control agent was harmful or of no help. In one case using 3cell of allyl alcohol the deposit was semibright but the addition of asulfonamide increased the brightness. This was not so for B- chloroallylalcohol where only 0.5 cell of the alcohol had to be used. The use ofN,N'-bis-(phenylsulfonyl)- 4,4'-biphenyldisulfonimide will eliminatemisplating caused by high concentrations of ethoxylated propargylalcohol but just as good deposits are obtained when lower concentrationsof the acetylenic compound are used with no sulfonimide. Another casewhere a control agent was beneficial was for 2-butyne-l,4-dithioethanol. These cases are rare however.

The use of certain sulfonate and sulfonamide control agents alone, inalkaline nickel solutions has little effect compared to when these areused in acid solutions. The deposit from alkaline solutions with noaddition agents present usually has more sheen than those from acidsolutions. This may be why the addition of such agents as benzenesulfonate, saccharin or allyl sulfonate very seldom exhibit anyimprovement in brightness. Sometimes, as for dibenzenesulfonamide theuniformity of lustre is improved but the increase in lustre is almostnegligible. Also the ductility is not improved.

In some cases there is an advantage in using the brighteners in thealkaline nickel solution. For example many of the acetylenic or olefiniccompounds such as diethylamino-3-butyne-4-ol or butenediol effect brightdeposits except at the high current density of about 70-80 asf.Ethylenecyanohydrin on the other hand gives brighter deposits at thehigher current density than at lower current density. Therefore there isan advantage in using say butenediol and ethylenecyanohydrin incombination.

The addition agents of the present invention comprise materials selectedfrom the group consisting of acrylonitrilepolyalkalene amine;1,6-Morpholino-2- hexyne; -Amino-2-benzimidazolethiol; Propiolic acid;Acetylenic substituted polyamines; B, B'- Thiodipropionitrile;Ethylenecyanohydrin;N-Allyl benzene sulfonamide; Acetylene dicarboxylicacid; Sodium phosphite; Triallyl propargyl ammonium perchlorate;Carboxymethylpyridinium iodide; 1- Diethylamino-4-acetoxy-2-butenesodium sulfonate; 2- Phenyl-2-cyanoethoxybutyne; N-Propargyl saccharin;Z-Mercaptobenzothiazole; and Acetonitrile.

These addition agents of the instant invention are utilized to advantagein alkaline nickel plating processes. Such a nickel plating process canutilize any conventional source of nickel as used in the platingindustry such as Nicl NiSO or NiBF wherein the pH is adjusted to betweenabout 7.0 and 11.0. Such plating baths can be operated generally in therange from room temperature to [80F depending on the particular typebath employed. Likewise, plating can be accomplished in such baths atcurrent densities of from about 5 to about 100 amps per sq. ft.

This invention will be more fully described by the following examples.They are given by way of illustration, but not of limitation. Unlessotherwise specified all temperatures are in Fahrenheit and all parts andpercentages are by weight.

EXAMPLE 1 A solution of the following composition and conditions wasused:

NiSo .6H,O I00 gll EDTA (Na) 40 gll (sodium slat of ethylene diaminetetra-acetic acid) Sodium Citrate 60 gll Ammonium Chloride 35 g/lTriethanolamine 35 gll pH 8.0 Temperature l40F EXAMPLE 2 To the abovesolution 0.005 gll of triallylpropargyl ammonium perchlorate was added.The deposit became brighter especially in the intermediate C. D. areas.When the brightener concentration was increased to 0.01 g/l there was afurther increase in brightness so that the -90 asf range was semibright.

EXAMPLE 3 To solution of Example 1, 0.1 g/l of carboxymethylpyridiniumchloride was added with slight brightening effect. When 0.4 gll wasused, the deposit was bright with some darkness in the low C. D. area.The addition of N,N'-bis(phenylsulfonyl)-4,4'-biphenyldisulfonimide hadpractically no effect. Operating without air agitation allowed thedeposit to be less uniform in brightness.

EXAMPLE 4 In the solution of Example 1 N-Propargyl saccharin, 0.1 g/leffected bright and stressed deposits with air agitation. With noagitation 0.25 g/l had to be used. Addition of saccharin was of nobenefit.

EXAMPLE 5 A nickel solution according to US Pat. No. 2,069,566 of thefollowing compositions was used:

NiSO,.6H,0 I20 gll Na P,0,.l0H,0 65 Sodium Citrate (2H,0) 60 Citric Acid15 NaCl 30 Nl-LOH Soln. (Sp. Gr. 88) 70 cell pH Temp. 50C; slow airagitation A bent panel was.plated at 20 asf average. The deposit wasbright from 1 to 12 asf and grey above this C. D. When 0.005 gll ofpropargyl alcohol was added the deposit was fully bright. When 0.3 g/lof coumarin was further added the deposit lost some lustre in the highC. D. area, i.e., 30-50 asf, where it might be described as semibright.

EXAMPLE 6 To the same basic solution as that used in Example 5, 0.006g/l of B, B'-thiodipropionitrile was added. This increased the brightlow C. D. range only to 1 to 15 asf, but the higher C.D. areas weresemibright instead of grey. Addition of 4 percentN,N'-bis(phenylsulfonyl)- 4,4-biphenyldisulfonamide has no effect. Theaddition of ethoxylated butyne diol made for a fully bright depositexcept that the high C. D. areas had a slight haze.

To further illustrate the difference between alkaline and acid nickelelectroplating baths, two addition agents of the instant invention,namely,- propiolic acid and acetylene dicarboxylic acid were added toacid nickel electroplating baths and were found to be ineffectivebrighteners in said acid nickel baths.

As stated earlier in the specification, any conventional source ofnickel may be used in supplying the nickel for the plating bath for theinstant invention. For example, nickel chlorate, nickel sulfate, nickeltetraborate, nickel carbonate, nickel hydroxide, nickel sulfamate andthe like. Commonly, complexing agents are used in such plating baths toproduce complex ions and such is suitable in the practice of the instantinven-

